setup_links.py: Add third_party/libFuzzer
setup_links.py: Add third_party/libFuzzer

This solves the GN error starting after rolling in
https://chromium.googlesource.com/chromium/src/+/cbd1cf202d289ccaf76aa67828e9425e5a061d6b
as part of https://codereview.webrtc.org/1855003002

BUG=chromium:591955
TBR=pbos@webrtc.org
TESTED=Ran the gn gen and refs steps locally + compiled succesfully.

Review URL: https://codereview.webrtc.org/1857673002 .

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#12211}

ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc